Neurological disorders represent a rapidly growing health burden on a global scale. In the United States there are approximately 7M people suffering from Alzheimer's, Parkinson's, multiple sclerosis, amyotrophic lateral sclerosis (ALS) and Huntington's diseases alone. These and many other neurodegenerative disorders (NDDs) do not manifest themselves until later in life;consequently, in 2030 one in five Americans will be over 65, therefore an estimated 12M may be suffering from NDDs by this time. To counteract the significant health burden and endemic suffering from NDDs, rapid advances in therapeutic development are needed. A significant advance in such therapies is the nascent short interfering RNA (siRNA), utilizing a small nucleotide molecule that targets a specific mRNA transcript for degradation. This treatment regimen is far from optimized, necessitating the advance of new siRNA delivery vehicles. More problematic is transport across the blood brain barrier (BBB) to effectively treat neurodegenerative pathologies. This research will significantly advance siRNA carrier design and specifically target the central nervous system (CNS) with contemporary, genetically engineered siRNA vehicles. Compulsory attributes for any siRNA delivery vehicle are (i) an efficient and protective condensation of the siRNA;(ii) explicit tissue- or cell-specific targeting;and (iii) a means of disassembly at said site in sufficient concentrations to elicit the desired pharmacological effect. These major obstacles will each be addressed in the novel recombinant carriers for siRNA delivery proposed. This critical progression could eventually revolutionize the state of neuropharmaceuticals. This research will develop genetically engineered siRNA carriers that will surpass the current line of siRNA vehicles by varying a predetermined set of cationic oligo (peptides) to examine the effect of modulating charge ratio and density on complex stability and transfection capability. Contemporary recombinant techniques will combine the optimal cationic oligo (peptide) sequence with a distinct selection of CNS-targeting peptides that will transcytose across the BBB for siRNA access to the brain parenchyma. In addition to rigorous physicochemical characterization, we will evaluate siRNA transfection efficiency with brain-derived primary cells (astrocytes) to mimic the cerebral compartment. Finally, transcytosis capability across a two- layer transwell in vitro model of the BBB to elucidate CNS-targeting potential will be tested. The research proposed is entirely novel, utilizing molecular biology alone to construct innovative siRNA carriers that will allow for large scale production, biocompatible degradation and modular modification, with the added propensity to overcome the surmountable challenges in drug delivery across the BBB. PUBLIC HEALTH RELEVANCE: siRNA is a leading nascent therapy, but its utility in the clinic is limited by the lack of suitable delivery vehicles. This proposal advances siRNA delivery one step further through the development of peptide-based siRNA carriers for eventual transport across the BBB for the ultimate treatment of NDDs. This siRNA therapy system consists of two parts: (i) siRNA against specific therapeutically relevant proteins and (ii) CNS-targeted siRNA carrier for rapid localization at the BBB and deployment of the siRNA therapeutic across the BBB to treat NDDs. These siRNA carriers will be designed entirely by genetic engineering providing rapid and large scale production, modular modification, highly specific CNS-targeting, and biocompatible degradation after payload delivery.